The applicants proposed to build an ultra-low-cost and high-quality prototype Prepolarized MRI scanner for diagnosing head tumors. The overall goal of this research is to develop a new and innovative imaging modality that shows great potential for cancer screening, diagnosis and image-guided treatment. The specific aims are to design and build both a homogeneous, low-field electromagnet and a lowfrequency receiver system optimized for head imaging. The final aim is to integrate these subsystems with our working Prepolarized MRI system and to obtain an image of a normal volunteers head. This research is intended to demonstrate that Prepolarized MRI system contrast and SNR are equivalent to a conventional 0.5 T MRI system; and that this high-quality Prepolarized MRI system will cost less than $50,000 in capital costs. The successful development and integration of this innovative technology will require the application of several principles of engineering and science. For example, a homogeneous electromagnet design method draws from both electromagnetics and linear programming. A low-noise receiver subsystem design designed by the applicants relies on the principles of optimal RF receiver electronics. Pulse sequence design relies on the principles of MRI physics.